Controller for electric hammers.



A. WENDELBURG.-

CONTROLLER FOR ELECTRIC HAMMERS.

Patented Apr. 9, 1918.

3 SHEETS-SHEET 1 APPLICATION FILED AUG.26, I914- 1,262,149.

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A. WENDELBURG.

CONTROLLER FOR ELECTRIC HAMMERS.

APPLICATION FILED AUG-26,1914.

1,262,149. Patented Apr. 9, 1918.

3 SHEETS-SHEET 2.v

WITNESSES 34,5

w W r I yfM A TTORNEYS UNITED STATES PATENT OFFICE.

ALEX WENDELBURG, OF NEW YORK, N. Y.,

ASSIGNOR TO PITTSBURGH ELECTRIC TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF PENNSYLVANIA.

Specification of Letters Patent.

Patented Apr. 9, 1918.

Application filed August 26, 1914. Serial No. 858,639.

To all whom it may concern:

Be it known that I, ALEX WENDELBURG, a citizen of the United States, residing in the city, county, and State of New York, have invented certain new and useful Improvements in Controllers for Electric Hammers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to circuit controlling means for electric hammers adapted for use in chipping, calking, riveting, cutting and other work requiring a rapid succession of blows upon a suitable tool. The invention is directed more particularly to provision of means for delivering current to the operating coils of the hammer at predetermined or suitable time intervals and in suitable quantity, the delivery of current being first to one coil and then to its opposing coil, sothat the plunger or reciprocating element of the hammer may be made to strike a succession of rapid blows on the tool or its carrier.

One of the features of the invention resides in the elimination of destructive sparking between the contact elements whereby the circuit to the hammer is established and then broken, and in the particular embodiment hereinafter described the arrangeme-nt is such that heavy currents may be established and then broken at relatively high frequency, and in a manner best adapted to insure long life of the circuit controller and best operation of the windings of the hammer.

Another feature of the invention resides in controlling the force of the hammer blow by controlling the length of time during which current can flow to one or the other of the windings of the hammer, and in the preferred embodiment hereinafter disclosed this control is effected by varying the efi'ective width of a live commutator segment, thereby increasing or decreasing the time during which current can flow at each cycle, and thereby varying the degree of magnetic saturation at the solenoid of the hammer, and thus varying the force of the blow.

The invention also provides for a compact arrangement of the several parts and for economical and effective driving of the movable elements, and includes means for auto- Figure 1 is an elevation of the circuit controlling means with the commutator and brush-supporting drum shown in section and one of the resistance boxes removed;

Fig. 2 is a side elevation of the commutator with the brushes removed and with a portion of the commutator broken away to expose the collector rings and one of the brush holders for said rings;

Fig. 3 is a plan view of the brush carrier showing the centrifugal governor used for regulating the pressure of the brushes on the commutator;

Fig. 4 is a transverse section through the brush carrier just outside of the slip rings;

Fig. 5 is a plan View of the stationary commutator; and

Fig. 6 is a diagram showing the electrical circuits of the apparatus and the relation of those circuits to the electric hammer to be operated.

In the construction illustrated, the motor 1 is a direct current motor with its field frame 2 secured to a pedestal 3 mounted on a platform 4. Secured to the side of the motor field by screws 5 is a ring 6 carried on the arms 7 of a spider, through the central hub of which passes the armature shaft 8 of the motor. This ring 6 is lined with insulating material and is provided with a collar 9 fastened in place by screws 10; collar 9 has an inwardly projecting flange 11 fitting within the ring 6 and serving to anchor the collar firmly in place. The ring 6 and collar 9 are shaped as shown in Fig. 1 to grip a double series of commutator segments, and between these segments is an anchoring ring 12 beveled on both sides to lock in place the two series of commutator segments.

Mounted on the outer end of the motor shaft 8, and keyed thereto, is a hub- 13 for outer end of which is closed a wall 14 made integral with said hub, and the inner end of which is open and encircles the body of motor 1. Openin 15 (Fig-2) throu h this drum are provided to receive brus holding blocks 16 (Fig. 3), which are fastened in place by screws 17 suitably 1I1Sl1- lated therefrom as shown in Fig. 4. These brush holders will each accommodate a plurality of brushes 18, say four in number, and the brushes of each set are yieldingly held against the commutator by a swinging block 19 mounted above the brush-holder on a pivot pin 20 and carrying springs 21, which press yieldingly on the tops of the brushes to hold them to their work. Associated withv each swinging block 19 is a rojection 22 serving as a counterweight to increase the pressure on the brushes as the motor increases in speed, thereby increasing the friction between the brushes and the commutator and preventing the motor from attaining a speed hi her than would be suitable for best operation of the electric hammer to be controlled.

As a means for varying the effect of weight 22 there is provided an adjustable auxiliary weight 23 threaded to weight 22 and movable outward to magnify the centrifugal effect. A lock nut 24 serves to hold weight 23 in position after adjustment thereof. The four brushes 18 of each group are connected together, and by flexible conductors 25 and 26 the two groups are connected respectively with slip rings 27 and 28 mount ed on an insulating collar 29 which encircles hub 13, and is fastened thereto by a suitable set screw. The means for establishing contact with slip rings 27 and 28 comprises a pair of diametrically opposite brushes each carried by a spring, one of which is shown in elevation in Fig. 2, where 30 is the brush held in a shallow pocket in the end of a yieldin plate 31 operating as a spring support. he other end of this plate is fastened by screws 32 to an insulating block which is anchored by screws 33 to one of the horizontal arms of the commutator spider, as indicated in Fig. 4. Plate 31 may be cut away between the brush socket and the supporting block, as indicated in Fig. 2, and may be curved between the brush and the block to increase its resilience.

The commutator is not of symmetrical construction but embodies a live segment 34 and a dead segment 35, and the latter may be supplemented by other dead segments 36 and 37. Interposed between the live segment 34 and the dead segment 35 are a series of auxiliary segments 341, 342, 343, etc., separated by intervening strips of insulation. This grouping of the segments is in duplicate.

Referring to Fig. 5, itwill be seen that driving the brush supporting drum, the

iliary segments of the commutator as indicated diagrammatically in Fig. 6. The resistances are in a progressively increasing series with the smallest resistance connected between the live segment 34 and its adjacent auxiliary segment 34", and the next larger resistance connected between auxiliary segment 34 and auxiliary segment 341, and so on through the series, as indicated in Fig. 6. In magnitude, these resistances are such that when a brush moves from live segment 34 toward dead segment 35, the current which might otherwise form a spark will be shunted through the resistance and thereby diminished in value but not immediately interrupted, and by continuing this pro ressive decrease in the current to the end 0 the series of auxiliary segments, the rotating brush can finally cross over to the dead segment 35 and break the circuit without sparking. In general, the resistances between adjacent segments are each made as large as possible and still prevent sparking when the brush is operating under full load conditions.

In addition to the auxiliary segments 341, 342, etc., and their complementary segments 34*, 34*, etc., there are provided supplementary segments 40, 41, 42, 43, 44, 45 and 46. These can be connected one by one, to live segment 34 so that they will serve as extensions of that segment and thereby increase the length of time during which current can be delivered to a brush as it rotates around the edge periphery of the commutator. In general, the single live segment 34 is of such width that when the motor is driving the brushes at a suitable speed, say 1750 revolutions per minute, the current taken from the live segment by the rotating brushes will be just suilicient to produce a light strikin blow at the hammer. The impedance ofi'ere by the windings of the hammer to the periodic current flow with which they are supplied holds back that current to such an extent that magnetic saturation of the solenoid plunger is not attained. By connecting to segment 34 one or more of the supplementary segments 40, 41, 42, etc., as by bridging the intervening insulation with solder, as indicated in Fig. 4 at 47, 48 and 49, the effective width of the live segment 34 is increased and the hammer will strike a proportionately harder blow. The possibility of thus increasing the effective width of segment 34 is particularly advantageous in adjusting for the particular voltage of the current to be used in actuating thehammer, for on voltages lower than standard, one or more supplementary segments may be soldered in to cause the hammer to strike its normal blow even when working on the lower than normal voltage.

In addition to the adjustments which may be made by soldering, there may be provided a hand switch 50, indicated diagrammatically in Fig. 6, with contact fingers 51, 52, 53 and 54, connected respectively with the supplementary segments 43 to 46, so that as the switch 50 is swung around, these supplementary segments may be electrically connected as a part of the live segment 34 and so will serve to increase the duration of current flow to the hammer.

In Fig. 6 the electric hammer is indicated diagrammatically as including a pair of opposed windings 55 and 56 suitably housed and connected to a common conductor 57, which leads through a digitly operated circuit breaker 58 and then through conductors 59 and 60 to one side of the current supply switch 61, which controls the flow of current from the source of energy, The other ends of windings 55 and 56 are connected respectively through conductors 62 and 63 to the slip rings 28 and 27. The motor 1 may also be connected across the same source of supply and controlled by switch 61.

The operation of the device is as follows:

Vhen switch 61 is closed, direct current at suitable voltage is admitted to drive motor 1 and rotate the brushes over the commutator. Also, by closing this switch 61, one side of each of the hammer windings 55 and 56 is connected to one side of the source of energy, say the positive side, and the hammer is ready for use. By closing with the thumb the switch 58 in the common return conductor 57 of the hammer coils, connection is established to both those coils and they will receive current alternately from the source of power through the commutator and its brushes, the magnitude and duration of the periodic flow of current in each coil being regulated by the speed of the motor and by adjustments at the commutator.

While a set of brushes is moving over the dead segments 35, 36' and 37 no current flows through them, but as soon as the brushes swing around into contact with live segment 34 they receive current for delivery to one or the other windings of the hammer, depending on which set of brushes is under consideration. The current flow does not instantly jump to its maximum value as calculated on the basis of voltage and ohmic resistance, because of the inductance offered secure a heavier blow, one or more of the segments 40 to 42 may be soldered to live segment 34, thereby'in efi'ect extending the width of that segment and increasing the time during which the magnetism of the hammer may build up toward saturation. But as a convenience in further regulating the blow of the hammer while in operation,

recourse may be had to switch 50, which, when swung around, will electrically connect one or more of the supplementary segments 43 to 46, so that they will in efi'ect form further extensions of live segment 34. With all these supplementary segments electri-- cally connected with live segment 34 by soldering or by switch 50, the current flow is of a duration long enough to allow the hammer to reach magnetic saturation and the plunger of the hammer strikes its maximum blow.

The current through the hammer windings may be of considerable magnitude, and its prompt interruption without arcing or destructive sparking is one of the great difiiculties overcome by the present apparatus; for when a set of brushes leaves live segment 34, it passes over a series of auxiliary segments all connected together and to the live segment 34 through resistances. Furthermore, these' resistances are of such pro gressively increasing value that the current flow is quickly reduced to such magnitude that it can be safely interrupted and the brushes allowed to pass over to dead segment 35. As an additional precaution dead segment 35 is supplemented. by additional dead segments 36 and 37 separated therefrom by insulation, so that any accidental bridging of the gap between the last auxiliary live segment and dead segment 35 will not seriously interfere with the operation, for if by such accident segment 35 becomes a live segment, the current will be interrupted as soon as the brushes pass over to segment 36, or failing in that, will be interrupted when the brushes pass to dead segment 37.

By making the commutator in duplicate, as indicated in Fig. 5, its current carrying capacity is increased, but in addition there is advantage in the staggered arrangement of the auxiliary se ents there illustrated. When a set of brus es moves from live segment 34, two of the four brushes encounter auxiliary segment 34* before the other two brushes encounter auxiliary segment 341, and similarly the trailing corners of the brushes leave the auxiliary segments alternately on first one side and then the other side of the two sets. There results an'interchange of current through the brushes by way of their common brush holder and conductor 25, and the resistances with which the auxiliary segments are respectively provided are cut into circuit first on one side of the commutator and then on the other, with the result that the change in current flow to the hammer is gradual and in small steps. By having the auxiliary segments in two sets arranged side by side in staggered relation, each bar can be of considerable width and with ample contact surface. The first resistance to be cut in circuit must be small because the current flowing to the hammer is large and the work circuit is of high inductance, and if the resistance were large the current would jump the insulation to the next auxiliary segment rather than go through the resistance; but after one resistance has been introduced into the circuit, the next resistance to be added can be of larger value because of the current reduction by the first resistance, and so on through the series, each added resistance being larger than any of its predecessors be cause of the reduction in current by the resistance immediately preceding. After ten or fifteen resistances have been laced in circuit with resultant reduction 0 the current, the remaining resistances may increase in magnitude at a higher rate so that the current is brought down to a low value as rapidly as possible.

In designing the apparatus, the resistances for the auxiliary segments are made as large as possible and still prohibit sparking at any of the gaps of the commutator, when the apparatus is running under any ordinary conditions, and to do this, account must be taken of the hammer design and the voltage of the source of current and the speed of the motor, because the inductive characteristics of the load circuit have a direct bearing on the speed at which the current can be interrupted safely at the commutator.

I claim:

1. A circuit controller for electric hammers comprising a support, a commutator fixed upon said support and having a live segment, a dead segment having one end adjacent to. said live segment, a plurality of auxiliary segments between the other end of said dead segment and said live segment, a resistance having its terminals directly connected to said live segment and the adjacent one of said auxiliary segments, other resistances having their terminals directly connected to adjacent auxiliary se ments, a pair of brushes movable over the edge periphery of said commutator and into and out of electrical connection with said live segment, a contact ring for each brush movable with and electrically connected to the brush, a fixed contact device engaging each of the contact rings, and circuit connections leading from each of the contact devices and adapted to be placed alternately in circuit with said live segment through the con tact rings and brushes.

2. A circuit controller for electric hammers comprising a support, a commutator fixed upon said support and having a live segment, a dead segment having one end adjacent to said live segment, a plurality of auxiliary segments between the other end of said dead segment and said live segment, a resistance having its terminals directly attached to said live segment and the adjacent one of said auxiliary segments, other resistances having their terminals directly attached to adjacent auxiliary segments and of magnitudes increasing progressively with the distance of said auxiliary segments from said live segment, a pair of brushes movable over the edge periphery of said commutator into and out of the electrical connection with said live segment, a contact ring for each brush movable with and electrically connected to the brush, a fixed contact brush engaging each of the contact rings, and C11- cuit connections leading from each of the fixed contact brushes and adapted to be placed alternately in circuit with said live segment through the contact rings and brushes.

3. A circuit controller for electric hammers comprising a commutator havmg a stationary live segment, a stationary dead segment, a plurality of supplementary segments between the live and dead segments, a pair of brushes movable over the edge periphery of said commutator into and out of electrical connection with said live segment, a contact ring for each brush movable with and electrically connected to the brush, a fixed contact device engaging each of the contact rings, circuit connections leading from each of the contact devices and adapted to be placed alternately in circuit with said live segment through the contact rings and brushes, and means for connecting any. desired number of sald supplementary segments to said live segment to vary the time during which current may pass to said circuit connections while the brushes are passing over the live segment and the connected supplementary segments.

4. A circuit controller for electric hammers, comprising a commutator having duplicate live segments, duplicatedead segments, duplicate series of auxiliary segments between each of said live and dead segments, the auxiliary segments of one series being staggered with respect to the corresponding segments ofthe otherseries, and duplicate series of resistances connecting together the segments of each of said series of auxiliary segments and having magnitudes increasing progressively from said live segments toward said dead segments.

5. A circuit controller for electric hammers, comprising a commutator having duplicate live and dead segments, duplicate series of auxiliary segments between each of said live and dead segments, the segments of one series being staggered with respect to the corresponding segments of the other series, resistances connecting adjacent segments of each series, and means for altering the relative extent of said dead and live segments.

6. A circuit controller for electric hammers comprising a commutator having a stationary live segment and a stationary dead segment,- a plurality of relatively narrow supplementary segments between one end of the live segment and one end of the dead segment, conductors connected to said live segment, and to each of said supplementary segments, contact members at the outer ends of the conductors, a pair of brushes movable over the edge periphery of said commutator into and out of electrical connection with said live segment, a contact ring for each brush movable with and electrically connected to the brush, a fixed contact brush engaging each of the contact rings, circuit connec tions leading from each of the fixed brushes and adapted to be placed alternately in circuit with said live segment through the contact rings and brushes, and means for con necting together any desired number of said contact members to connect the corresponding number of supplementary segments to said live segment to vary the time during which current may pass to said circuit con nections while the brushes are passing over the live segment and the connected supplementary segments.

7. A circuit controller for electric hammers comprising in combination a support, a stationary live segment mounted upon the support, a stationary dead segment mounted upon the support, a plurality of relatively narrow auxiliary segments mounted on the support between one end of the live segment and one end of the dead segment, a plurality of resistance units, one of which has its terminals connected to the live segment and the adjacent auxiliary segment, and the others of which have their terminals directly connected to adjacent auxiliary segments, a plurality of relatively narrow supplementary segments between the other end of the live segment and the other end of the dead segment, a pair of brushes movable over the edge periphery of said commutator into and out of electrical connection with said live segment, a contact ring for each brush movable with and electrically connected to the brush, a fixed contact brush engaging each of the contact rings, circuit connections leading from each of the fixed brushes and adapted to be placed alternately in circuit with said live segment through the contact rings and brushes, and means for connecting any desired number of supplementary segments to the live segment to vary the time during which current may pass to said circuit connections while the brushes are passing over the live segment and the connected supplementary segments.

8. A circuit controller for electric hammers comprising in combination a support, a

stationary live segment mounted upon the support, a stationary dead segment mounted upon the support, a plurality of relatively narrow auxiliary segments mounted on the V 7 support between one end of the live segment and one end of the dead segment, a plurality of resistance units, one of which has its terminals connected to the live segment and the adjacent auxiliary segment and the others of which have their terminals directly connected to adjacent auxiliary segments, said units having resistance values increasing in magnitude progressively from the live toward the dead segment, a plurality of relatively narrow supplementary segments between the other end of the live segment and the other end of the dead segment, conductors connected to said live segment and to each of said supplementary segments, contact members at the outer ends of the conductors, a pair of brushes movable over the edge periphery of said commutator into and out of electrical connection with said live segment, a contact ring for each brush movable with and electrically connected with the brush, a fixed contact brush engaging each of the contact rings, circuit connections leading from each of the fixed brushes and adapted to be placed alternately in circuit with said live segment through the contact rings and brushes, and means for connecting together any desired number of contact members to connect the corresponding number of supplementary segments to said live segment to vary the time during which current may pass to said circuit connections while the brushes are passing over the live segment and the connected supplementary segments. In testimony whereof I aflix my signature lll presence of two witnesses.

ALEX WENDELBURG. Witnesses:

D. S. EDMoNDs, LEON W. ROSENTHAL. 

